Ship unloaders, at the lower end of which a cargo pickup member in the form of a digging head rotating around its vertical axis is located, are known from German Publication P 41 16 467.9 and P 41 25 109.1. This cargo pickup member transfers the bulk material radially in the inward direction onto a first elevator, which may be, e.g., a screw conveyor.
This screw conveyor consists of a preferably double-threaded screw and a pipe closely surrounding same. The bulk material penetrated into the screw threads is pressed against the inner wall of the pipe and pushed upward by the pitch of the screw.
Once the bulk material reaches an opening arranged at the top of the pipe, the bulk material leaves the screw through a transfer duct and enters the pickup area of the second elevator in the ship unloader trunk.
As long as bulk materials are present on the bilge of the ship in sufficient amount and at sufficient dumping height, the bulk material is continuously picked up by the cutter head of the screw conveyor, delivered upward by the screw within the screw pipe, and transferred through the transfer duct onto the second elevator in the ship unloader trunk. Near the end of the unloading process, shovel loaders or auxiliary staff with manual devices are used in order to remove residual cargo especially from the corners and to bring it into the area of the cargo pickup device.
The performance of these residual tasks is time-consuming and labor-intensive.